Makindo Medical Notes

Overview of the Femoral Nerve

The femoral nerve is one of the major peripheral nerves of the lower limb. It arises from the lumbar plexus and provides motor and sensory innervation to parts of the thigh and lower leg. It is essential for movements such as hip flexion and knee extension. The femoral nerve originates from the lumbar plexus, specifically from the posterior divisions of the L2, L3, and L4 spinal nerves.

Origin and Course

• Origin:
  • Arises from the posterior divisions of the L2, L3, and L4 spinal nerves within the lumbar plexus.
• Course:
  • Descends through the psoas major muscle and emerges from its lateral border.
  • Passes underneath the inguinal ligament to enter the thigh, where it lies lateral to the femoral artery and vein.
  • Divides into several branches in the femoral triangle, providing motor and sensory innervation.

Branches of the Femoral Nerve

• Muscular Branches:
  • Innervate the iliacus, pectineus, sartorius, and quadriceps femoris muscles.
• Cutaneous Branches:
  • Anterior cutaneous branches: Provide sensation to the anterior and medial aspects of the thigh.
• Saphenous Nerve:
  • The longest branch of the femoral nerve, providing sensory innervation to the medial aspect of the leg and foot.

Functions of the Femoral Nerve

• Motor Functions:
  • Iliacus: Flexes the hip.
  • Pectineus: Assists in hip flexion and adduction.
  • Sartorius: Flexes, abducts, and laterally rotates the hip; flexes the knee.
  • Quadriceps femoris: Extends the knee.
• Sensory Functions:
  • Provides sensation to the anterior and medial thigh through the anterior cutaneous branches.
  • Provides sensation to the medial leg and foot through the saphenous nerve.

Clinical Relevance

• Femoral Nerve Injury:
  • Can result from trauma, pelvic fractures, or surgical procedures.
  • Symptoms include weakness in hip flexion and knee extension, along with sensory loss in the anterior and medial thigh and medial leg.
• Meralgia Paresthetica:
  • Involves compression of the lateral femoral cutaneous nerve, a branch of the femoral nerve, leading to pain, tingling, or numbness in the lateral thigh.
• Clinical Testing:
  • Motor function can be assessed by testing the strength of hip flexion and knee extension.
  • Sensory function can be evaluated by testing sensation in the areas innervated by the femoral nerve and its branches.

Diagnostic Evaluation

• Clinical Examination:
  • Assessment of muscle strength and sensory function in the areas innervated by the femoral nerve.
• Electrophysiological Tests:
  • Electromyography (EMG) and nerve conduction studies to evaluate nerve function and identify the site of injury.
• Imaging:
  • MRI or ultrasound to visualize the nerve and surrounding structures, especially in cases of suspected nerve compression or injury.

Summary

The femoral nerve is a major nerve of the lower limb, responsible for motor innervation of the iliacus, pectineus, sartorius, and quadriceps femoris muscles, and sensory innervation to the anterior and medial thigh, medial leg, and foot. It originates from the lumbar plexus and travels through the thigh, dividing into several branches. Clinical conditions affecting the femoral nerve include femoral nerve injury and meralgia paresthetica. Diagnosis involves clinical examination, electrophysiological tests, and imaging studies.